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Get Head Set from Java TreeSet example

  1. /*
  2.   Get Head Set from Java TreeSet example
  3.   This Java Example shows how to get the portion of TreeSet containing the values
  4.   less than the specified value using headSet method of Java TreeSet class.
  5. */
  6.  
  7. import java.util.SortedSet;
  8. import java.util.TreeSet;
  9.  
  10. public class GetHeadSetFromTreeSetExample {
  11.  
  12.   public static void main(String[] args) {
  13.  
  14.     //create TreeSet object
  15.     TreeSet tSet = new TreeSet();
  16.    
  17.     //add elements to TreeSet
  18.     tSet.add("1");
  19.     tSet.add("3");
  20.     tSet.add("2");
  21.     tSet.add("5");
  22.     tSet.add("4");
  23.  
  24.     /*
  25.       To get a Head Set from Java TreeSet use,
  26.       SortedSet headSet(Object fromElement) method of Java TreeSet class.
  27.      
  28.       This method returns the portion of TreeSet containing elements less than
  29.       fromElement.
  30.  
  31.       Please note that, the SortedSet returned by this method is backed by
  32.       the original TreeSet. So any changes made to SortedSet will be
  33.       reflected back to original TreeSet.
  34.     */
  35.    
  36.     SortedSet sortedSet = tSet.headSet("3");
  37.    
  38.     System.out.println("Head Set Contains : " + sortedSet);
  39.    
  40.   }
  41. }
  42.  
  43. /*
  44. Output would be
  45. Head Set Contains : [1, 2]
  46. */